Magnetic tape recording and playback device with spring actuated head placement

ABSTRACT

In a magnetic tape recording and playback device, a resilient body is engaged with a head base. At the time of recording and playing back a tape, the head base is pressed and fixed when the resilient member is directly pushed by a drive plate, and at the time of withdrawing the head, the head base driven by the drive plate, through the resilient member, and the head base is pressed and fixed. In this way, a force given to the resilient body is reduced at the time of head base movement. It is possible to reduce the required head base drive force at the time of head base movement.

This application is a divisional of copending application Ser. No.08/229,771, filed on Apr. 19, 1994, pending, the entire contents ofwhich are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a cassette type tape recorder to whicha tape cassette accommodating a magnetic tape is applied, and moreparticularly relates to a mechanism by which a magnetic head is pulledout and withdrawn.

FIGS. 11 and 12 are plan views showing a conventional magnetic taperecording and playback device disclosed, for example, in JapaneseUnexamined Patent Publication No. 60-113349. FIG. 11 is a view showingthe condition of withdrawal, and FIG. 12 is a view showing the conditionof advance in the case where the tape is recorded and played back.

Next, the operation will be explained as follows.

FIGS. 11 and 12 show a mechanism for moving a magnetic head mountingplate 102 from a withdrawal position (stopping position) to an advanceposition (acting position). A drive gear 189 is attached onto thereverse side of a primary base plate (not shown in the drawing) close toa gear 138. This drive gear 189 includes: a resting section 190 in whicha portion of the gear is cut away; a spring receiving protruding section191 formed on the upper surface side; a spiral rotary cam 192 providedon the lower surface side; and a stopping time engaging section 193 alsoprovided on the lower surface side. A stopper wall 194 is protruded froma lower surface peripheral section of the drive gear 189. Further, anacting time engaging section 195 is protruded at a position close to thestopping time engaging section 193.

In this connection, a movable iron core 110a of a magnet plunger 110 ispushed in the extended direction by a coil spring 110b at all times.When a solenoid is energized with current due to the insertion of acassette, the movable iron core 110a is withdrawn into the solenoid. Inthe drawings, numeral 196 is an engagement lever, one end of which is acam engaging section 196a, and the other end of which is a plungerengaging section 196b. The plunger engaging section 196b is engaged witha fore end portion of the movable iron core 110a of the magnet plunger110, and the cam engaging section 196a is disposed along the lowersurface of the rotary cam 192. In the drawings, numeral 197 is a leafspring (a rod spring may be used), the free end of which comes intopressure contact with the spring receiving protruding section 191 sothat a torque is given to the drive gear 189 to rotate itcounterclockwise in the drawings.

Further, in the drawing, numeral 198 is a cam lever, which is rotatablypivoted on the reverse side of the primary base plate. At one end of thecam lever 198, a cam follower 198a is provided coming into contact withthe cam surface of the rotary cam 192. A rod spring 199, the modulus ofelasticity of which is high, is attached to this cam lever 198, and afore end portion of this rod spring 199 is engaged with a portion of themagnetic head mounting plate 102. In this connection, numeral 200 is atension spring for returning the magnetic head mounting plate 102 fromthe acting position to the stopping position. By the resilient force ofthis tension spring 200, the cam follower 198a is pressed onto the camsurface of the rotary cam 192.

Therefore, at the stopping time, as illustrated in FIG. 12, the camengaging section 196a of the engaging lever 196 is engaged with thestopping time engaging section 193, and the resting section 190 isopposed to the gear 138. A resilient force of the leaf spring 197 isactivated on the spring receiving protruding section 191, so that atorque is given to the drive gear 189 to rotate it counterclockwise inthe drawing. The cam follower 198a is located at a position where theradius of the rotary cam 192 is minimum. Consequently, the magnetic headmounting plate 102 is maintained at the withdrawal position (stoppingposition) by the action of the tension spring 200.

When a tape cassette is inserted into the device under the abovecondition, the solenoid of the magnet plunger 110 is energized withcurrent, and the engaging lever 196 is rotated by the operation of themovable iron core 110a, so that the cam engaging section 196a isreleased from the stopping time engaging section 193, and the drive gear189 is slightly rotated by the action of the leaf spring 197 and meshedwith the gear 138. Therefore, the rotation of the gear 138, that is, therotation of the motor is transmitted to the drive gear 189, and thedrive gear 189 is rotated clockwise approximately by one revolution.During the rotation of the drive gear 189, the cam follower 198a ismoved to the maximum radius portion of the rotational cam 192, and thecam lever 198 is greatly rotated, so that the magnetic head mountingplate 102 is moved to an advance position, resisting a force of thetension spring 200 (shown in FIG. 12). At this time, the cam engagingsection 196a is engaged with the acting time engaging section 195, sothat the drive gear 189 is stopped. However, the resting section 190 isopposed to the gear 138 again, and the leaf spring 197 comes intopressure contact with the spring receiving protruding section 191.Therefore, a torque is given to the drive gear 189 so as to rotate itcounterclockwise. The device is maintained under the above condition.

In order to provide a stopping condition, an electric current suppliedto the magnet plunger 110 may be stopped. Simultaneously when theelectric current is stopped, the movable iron core 110a returns to theextended direction, and the cam engaging section 196a of the engaginglever 196 is released from the acting time engaging section 195.Therefore, the drive gear 189 is a little rotated by the action of theleaf spring 197, and the cam follower 198a drops to the minimum radiussection of the rotary cam 192. Accordingly, the head panel 102 isreturned to the stopping position by the action of the return spring200.

In this connection, there is provided a mechanism (not shown in thepresent drawing); but illustrated in J60-113349 by which the rotaryplates, are rotated and linked with the withdrawal motion of themagnetic head mounting plate 102, so that the right and left gears areseparated from the adjacent gears. Therefore, simultaneously when themagnetic head mounting plate 102 is returned to its original position,the torque transmission path from the motor to both reel shafts, isinterrupted.

Whereas the conventional magnetic tape recording and playback device isconstructed in the above manner, the head mounting base plate is pulledin the withdrawal direction at all times, and when the head mountingbase plate is advanced, its advancing direction is the same as theextending direction of the spring used for withdrawal of the headmounting base plate. Consequently, the more the head mounting base plateis pulled out, the more the pulling force to pull out the head mountingbase plate is increased. When the head mounting base plate is pulledout, it is necessary to resist the force of the spring used forwithdrawing the head mounting base plate. Accordingly, it is necessaryto provide a spring having a very high modulus of elasticity. Therefore,in the case of tape recording and playback, it is necessary to pull outand hold the magnetic head mounting base plate, resisting the maximumspring force which includes the maximum tension of the head mountingbase plate withdrawal spring, and the spring force corresponding to thedeflection of the head mounting base plate pulling spring. Theconventional device has the above problems.

SUMMARY OF THE INVENTION

The present invention has been achieved to solve the above problems. Itis an object of the present invention to provide a magnetic taperecording and playback device characterized in that: the head mountingbase plate drive springs are integrated into one unit; a spring forcecan be individually given in each case of the time of tape recording andplayback and the time of head withdrawal; and the spring force can bedetermined to a minimum in the movement of the head mounting base platesuch as advance and withdrawal of the head, so that the drive force ofthe head mounting base plate can be reduced.

The present invention provides a magnetic tape recording and playbackdevice comprising: a head base to which a magnetic head is attached forrecording and playing back a cassette tape, the head base being capableof moving on a main base; a resilient body provided on the head base;and a lever having two ends, the first end of which is engaged with agroove formed on a disk-shaped cam for moving the head base, and thesecond end of which is engaged with the head base directly or throughthe resilient body.

Also, the present invention provides a magnetic tape recording andplayback device comprising: a head base to which a magnetic head isattached for recording and playing back a cassette tape, the head basebeing capable of moving on a main base; a drive plate having two ends,the first end of which is engaged with a groove formed on a disk-shapedcam provided on the main base for moving the head base, the drive platebeing capable of moving in a radial direction of the disk-shaped camwhen the groove is moved; and a resilient body engaged with both thedrive plate and head base at two points located in the movementdirection.

Also, the present invention provides a magnetic tape recording andplayback device comprising: a head base to which a magnetic head isattached for recording and playing back a cassette tape, the head basebeing capable of moving on a main base; a resilient body provided on thehead base; and a lever, having two ends, the first end of which isengaged with a groove formed on a disk-shaped cam, the groove being usedfor moving the head base, and the second end of which is engaged withthe head base through the resilient body.

According to the present invention, in the case where the head iswithdrawn, when the second end of the lever directly engages with thehead base and pushes it, the head base is pushed in a direction in whichthe head being separated from the attached cassette tape, and at thesame time one end of the resilient body engages with the engagingportion on the main base, so that a resilient force is given in adirection opposite to the direction in which the head is separated fromthe attached cassette tape. In the case of tape recording and playback,the second end of the lever pushes the head base through the resilientbody in a direction in which the attached cassette tape is pressed, andduring an interval between the time of head withdrawal and the time ofrecording and playing back a tape, the pushing force is reduced.

Also, according to the present invention, in the case of headwithdrawal, when the lever is moved in the radial direction, theresilient body pushes the head base in a direction in which the head isseparated from the cassette tape attached to the head base. In the caseof tape recording and playback, the resilient body pushes the head in adirection in which the head is pressed against the attached cassettetape when the lever is moved in the radial direction and also moved inthe opposite direction, and during an interval between the time of headwithdrawal and the time of recording and playing back a tape, thepushing force is reduced.

According to the present invention, in the case of head withdrawal, thesecond end of the lever is engaged with the head base through theresilient body so that the head base is pushed. Therefore, the head baseis pushed in a direction in which the head is separated from theattached cassette tape while a reaction force corresponding to thepushing force is being given by the resilient body. In the case of taperecording and playback, when the second end of the lever pushes the headbase through the resilient body, the head is pressed against theattached cassette tape while a reaction force corresponding to thepushing force is being given by the resilient body, and the pushingforce is reduced during an interval between the time of head withdrawaland the time of recording and playing back a tape.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing the condition of head withdrawal of themagnetic tape recording and playback device of an embodiment of thepresent invention.

FIG. 2 is a view showing the condition of head movement of the magnetictape recording and playback device of an embodiment of the presentinvention.

FIG. 3 is a view showing the condition of tape recording and playingback of the magnetic tape recording and playback device of an embodimentof the present invention.

FIG. 4 is a view showing the head withdrawal condition of anotherembodiment of the present invention.

FIG. 5 is a view showing the condition of head movement of anotherembodiment of the present invention.

FIG. 6 is a view showing the condition of recording and playing back ofanother embodiment of the present invention.

FIG. 7 is a view showing the condition of head withdrawal of anotherembodiment of the present invention.

FIG. 8 is a view showing the condition of head movement of anotherembodiment of the present invention.

FIG. 9 is a view showing the condition of recording and playing back ofanother embodiment of the present invention.

FIG. 10(a) is an overall arrangement view of an embodiment of themagnetic tape recording and playback device of the present invention.

FIG. 10(b) is an overall view of the inventive portion.

FIG. 11 is a view showing the condition of head withdrawal of aconventional magnetic tape recording and playback device.

FIG. 12 is a view showing the condition of tape recording and playingback of the conventional magnetic tape recording and playback device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1

FIG. 10(a) is an overall perspective view of the magnetic tape recordingand playback device of the present invention. FIG. 10(b) is a plan viewshowing the entire inventive portion. FIGS. 1, 2 and 3 are plan viewsshowing an embodiment of the present invention. FIG. 1 shows awithdrawal condition of the head, FIG. 2 shows a movement condition ofthe head, and FIG. 3 shows a recording and playback condition of thehead. In the drawings, numeral 10 is a magnetic head (also referred toas a head), numeral 20 is a magnetic head mounting base plate (alsoreferred to as a head base), numerals 11, 12 are engaging members forengaging the magnetic head 10 with the magnetic head mounting base plate20, numerals 21, 22, 23 denote a spring hook integrated with themagnetic head mounting base plate 20, numerals 24, 25, 26 are slidingguide holes formed in the longitudinal direction of the magnetic headmounting base plate 20, numerals 24a, 26a are advance stopper sectionsof the magnetic head mounting base plate, numeral 27 is an end surfacefor driving the magnetic head mounting base plate, numeral 30 is a drivelever of the magnetic head mounting base plate (the drive lever is alsoreferred to as a lever), numeral 31 is a pin vertically provided on thedrive lever 30, numeral 32 is a lever end surface A which is a contactportion where the drive lever 30 and spring 40 are contacted, numeral 33is a lever end surface B which is a contact portion between the drivelever 30 and the end surface 27 of the magnetic head mounting base 20,numeral 34 is a rotary shaft of the drive lever 30, numeral 40 is aspring for pressing the magnetic head mounting base plate (the spring isalso referred to as a resilient body), numeral 41 is a fore end portionof the spring in the longitudinal direction, numeral 42 is a springportion hooked by the spring hook 22, numeral 50 is a disk-shaped rotarycam gear having a cam groove (the disk-shaped rotary cam gear is alsoreferred to as a disk-shaped cam), numeral 51 is a groove portion usedfor recording and playing back of a magnetic tape, numeral 52 is agroove portion for withdrawing the magnetic tape, numerals 53, 53a aregroove portions for moving the head, numeral 60 is a deck base (the deckbase is also referred to as a main base), numeral 61 is a plate membervertically provided on the deck base for engaging the spring used forpressing the head base plate mounting base, and numerals 62, 63, 64 areguide pins for guiding the magnetic head mounting base plate 20.

In the magnetic tape recording and playback device constructed in themanner described above, in the case where the head is in the withdrawalcondition as shown in FIG. 1, the center of the drive lever 30 isregulated by the rotary shaft 34, and the pin 31 vertically provided onthe drive lever is engaged with and regulated by the groove portion 52for withdrawing the head of the rotary cam gear 50, so that the positionof the drive lever 30 can be determined. At this time, the lever endsurface B 33 comes into contact with the end surface 27 for driving themagnetic head mounting base plate, so that the position of the magnetichead mounting base plate 20 can be regulated in the advance direction.At this time, the position of the spring 40 is regulated with respect tothe plane and height directions by the hooks 21, 22, and the height ofthe spring 40 is regulated by hook 23 so that the spring 40 ispreviously pushed in the opening direction. The fore end portion 41 ofthis spring 40 is engaged with and pressed by the plate member 61vertically provided on the deck base. Therefore, the magnetic headmounting base plate 20 is pushed in the advance direction.

Also, the position of the magnetic head mounting base plate 20 isregulated in the transverse direction by the action of the guide grooves24, 25, 26.

As a result of the foregoing, the position of the magnetic head mountingbase plate 20 is regulated and fixed. Under the condition describedabove, the pin 31 gives a load to the groove 52 of the gear 50 in thedirection of the gear center 58.

Next, the head movement condition shown in FIG. 2 will be explained asfollows.

When the drive motor and drive gear (not shown) are rotated in thecondition shown in FIG. 1, the rotary cam gear 50 is rotatedcounterclockwise. In this way, the condition shown in FIG. 1 is changedto the condition shown in FIG. 2. When the rotary cam gear 50 is rotatedin this way, the drive lever 30 is rotated counterclockwise, and thehead mounting base plate 20 advances.

In FIG. 2, when the pin 31 vertically provided on the drive lever isengaged with and regulated by the groove 53 for moving the head of therotary cam gear 50, the position of the drive lever 30 can bedetermined.

At this time, the spring 40 previously pushed in the opening directionis regulated and fixed by the spring hook 23 integrated with themagnetic head mounting base plate. Further, the lever surfaces A32 andB33 of the lever 30 are provided in an engaging portion by the action ofthe fixed spring 40 and the end surface 27 for driving the magnetic headmounting base plate. Therefore, the position of the magnetic headmounting base plate 20 can be regulated in the transverse direction.

As described above, the lever 30 is provided in an engaging portion bythe action of the spring 40 and the magnetic head mounting base platedrive end surface 27. Therefore, under the above condition (in thesection between the head withdrawal and the movement, and also in thesection between the movement and the recording and playback), the loadgiven to the lever 30 can be minimized, and further the rotational loadgiven to the rotary cam gear 50 can be minimized.

Next, the tape recording and playing back condition shown in FIG. 3 willbe explained.

When the drive motor and drive gear (not shown) are rotated in thecondition shown in FIG. 2 (or FIG. 1), the rotary cam gear 50 is rotatedcounterclockwise. In this way, it is changed to the tape recording andplayback condition shown in FIG. 3. When the rotary cam gear 50 isrotated, the drive lever 30 is rotated counterclockwise, and the headmounting base plate 20 is advanced.

In FIG. 3, when the pin 31 vertically provided on the drive lever isengaged with and regulated by the tape recording and playback grooveportion 51 of the rotary cam gear 50, the drive lever 30 can bepositioned. At this time, the magnetic head mounting base plate stoppers24a, 26a come into contact with the guide pins 63, 64, so that theadvancing motion of the magnetic head mounting base plate 20 is stopped,and the spring 40 engaged with this magnetic head mounting base plate20, previously pushed to the opening direction, is pushed to the closingdirection by the action of the lever end surface A 32. Therefore, themagnetic head mounting base plate 20 is set in a tape recording andplayback condition in which the base plate 20 is pushed forward andfixed. Since the lever 30 is pushed forward, the rotary cam gear 50impresses a force in the outer circumferential direction with respect tothe gear center 58, so that the rotary cam gear 50 works as a rotationalload.

Embodiment 2

FIG. 4 is a plan view showing another embodiment. Numerals 10 to 12, 20to 24, 24a, 25, 50 to 53, 53a, 58, 60, 62 and 63 are the same as thoseshown in Embodiment 1. Numeral 24b is a withdrawal stopper of themagnetic head mounting base plate 20, numeral 28 is a base plate springhook A of the magnetic head mounting base plate 20, numeral 29 is a baseplate spring hook B of the magnetic head mounting base plate 20, numeral35 is a drive plate, numeral 36 is an engaging pin to engage with thecam groove of the rotary cam gear 50, the engaging pin 36 beingvertically provided on the drive plate 35, numeral 37 is a plate springhook A of the drive plate 35, numeral 38 is a plate spring hook B of thedrive plate, and numeral 45 is a tension spring, one hook of which isengaged with both the base plate spring hook A 28 and the plate springhook A 37 which are adjacent to each other, and the other hook of whichis engaged with both the base plate spring hook B 29 and the platespring hook 38 which are adjacent to each other, so that the tensionspring 45 is provided between the hooks.

Under the head withdrawal condition shown in FIG. 4, the drive plate 35can push the magnetic head mounting base plate 20 in the withdrawaldirection when the drive plate 35 is fixed by the rotary cam gear 50 ata position which is more withdrawn than the base plate spring hooks A 28and B 29 adjacent to the plate spring hooks A 37 and B 38. At this time,the magnetic head mounting base plate 20 which is pushed is fixed whenthe withdrawal stopper 24 comes into contact with the guide pin 63. Inthis condition, the rotary cam gear 50 is given a force by the engagingpin 36 in the direction of the gear rotational center 58, so that thegiven force becomes a rotational load.

Under the condition shown in FIG. 5 in which the head is moved, thelongitudinal position of the magnetic head mounting base plate 20 is notregulated by the guide pin. Therefore, the spring hooks adjacent to eachother are arranged at the same position by the action of the tensionspring 45, so that no load is given to the rotary cam gear 50.Accordingly, the rotational load of the gear can be minimized.

At the tape recording and play back position shown in FIG. 6, the driveplate 35 is fixed by the rotary cam gear 50 at a position which is moreadvanced than the base plate spring hooks A 28 and B 29 adjacent to theplate spring hooks A 37 and B 38. Therefore, the magnetic head mountingbase plate 20 can be pushed in the advance direction. At this time, thepushed magnetic head mounting base plate 20 is fixed when the advancestopper 24a comes into contact with the guide pin 63. Under thiscondition, the rotary cam gear 50 is given a force by the engaging pin36 in an outer direction with respect to the rotational center 58, sothat this force becomes a rotational load.

Embodiment 3

FIG. 7 is a plan view showing another embodiment. Numerals 10 to 12, 20to 26, 30, 31, 34, 50 to 53, 60 to 64 are the same as those shown inEmbodiments 1 and 2. Numeral 27a is a post vertically provided on themagnetic head mounting base plate 20, numeral 39 is a drive springengaging hook provided on the lever 30, numeral 46 is a drive springhooked at the drive lever wherein the drive spring 46 is previouslypushed in a direction so that its opening angle is directed in a closingdirection, numeral 47 is a drive portion of the drive spring 46 used inthe case of tape recording and playback operation. Numeral 48 is a driveportion of the drive spring 46 in the case of withdrawal of the head.The drive spring 46 is installed in such a manner that the post 27a andthe hook 39 are interposed between the drive portions 47 and 48 formedinto the forked construction.

In the head withdrawal condition shown in FIG. 7, when the verticallyprovided post 27a is pushed by the head withdrawal drive portion 48 ofthe drive spring 46 in the withdrawal direction, the magnetic headmounting base plate 20 is fixed by the contact of the withdrawal stopper24b and the guide pin 63. Under the above condition, a force is given tothe rotary cam gear in a direction of the gear center 58, so that theforce becomes a rotational load.

In the head movement condition shown in FIG. 8, the position of themagnetic head mounting base plate 20 is not longitudinally regulated bythe guide pin. Therefore, the drive spring is in the most closedcondition, so that the loads of the drive lever 30 and rotary cam gear50 are minimized.

In the type recording and playback condition shown in FIG. 9, when thevertically provided post 27a is pushed by the tape recording andplayback drive section 47 of the drive spring 46 in the advancedirection, the magnetic head mounting base plate 20 is fixed by thecontact of the advance stopper 24a and the guide pin 63.

Under the above condition, a force is given to the fixed cam gear in adirection outside of the gear center 58, so that the force becomes arotational load.

As described above, according to the present invention, the head base ispositively pushed in one direction by the lever and resilient body atthe time of head withdrawal and also at the time of recording andplaying back a tape, and while the head base is being moved in aninterval from the time of head withdrawal to the time of recording andplaying back a tape, this pushing force can be reduced.

What is claimed is:
 1. A magnetic tape recording and playback deviceinto which a magnetic tape cassette may be inserted comprising:a mainbase; a head base to which a magnetic recording/playback head isattached, said head base being movable on said main base; an actuatingcam provided on said main base, for effecting movement of said headbase, between an engaged position and a disengaged position, relative tosaid magnetic tape cassette; a drive plate disposed laterally adjacentto said head base and engaged with said cam, said drive plate beingmovable in accordance with the rotation of said cam; and a resilientmember engaged with both said drive plate and head base at two pointslocated on the adjacent portions of said drive plate and said head base,such that when said cam is rotated said drive plate drives said headbase in a first direction parallel to the movement direction of saiddrive plate through said resilient member.
 2. The device according toclaim 1, wherein said resilient member biases said head base relative tosaid drive plate so as to correct misalignment therebetween in adirection perpendicular to said movement direction.
 3. The magnetic taperecording and playback device according to claim 1, wherein saidresilient member is a tension spring.
 4. The magnetic tape recording andplayback device according to claim 3, wherein rotation of said camcauses said spring to move sequentially through states of elongation,relaxation and elongation.
 5. The magnetic tape recording and playbackdevice according to claim 1, wherein during an interval between the timeof conveyance of said magnetic tape cassette into or out of said deviceand the time of tape recording and playback, a resilient force on saidresilient member is minimized.
 6. The magnetic tape recording andplayback device according to claim 1, wherein said cam is a disk-shapedcam having a groove on a flat surface thereof.
 7. A magnetic taperecording and playback device into which a magnetic tape cassette may beinserted, comprising:a main base; a head base to which a magneticrecording/playback head is attached, said head base being movable onsaid main base; an actuating cam provided on said main base, foreffecting movement of said head base between an engaged position and adisengaged position, relative to said magnetic tape cassette; aresilient member engaged with said head base at two points located inthe movement direction of said head base; and a drive plate disposedadjacent to said head base, engaged with both said cam and saidresilient member, so as to elastically connect said head base with saidcam, said drive plate being movable in a radial direction relative tosaid actuating cam, in accordance with rotation of said cam and in adirection parallel to the movement direction of said head base, therebydriving said head base in the movement direction.